iseeyour.cash stable version features 'Rich Rankings' and Twitter support
In short, iseeyour.cash is a search engine where anyone can search for a Twitter or Reddit username and see if they have any cryptocurrency addresses linked to their username. If they have, you can see their funds.
pluja3 has created this project in an effort to make it clearer to everyone that crypto is indeed not private and encourage people to explore Monero:
This platform has been built to raise concern about the public transparent blockchains such as Bitcoin or Ethereum. Most people think crypto is private, but it is not. Just using a username, you can see their funds.